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Use of intestinal Pseudomonas aeruginosa in fish to detect the environmental pollutant benzo[a]pyrene

Karami A, Christianus A, Ishak Z, Shamsuddin ZH, Masoumian M, Courtenay SC

J Hazard Mater, 2012 May 15;215-216:108-14.
PMID: 22417397 DOI: 10.1016/j.jhazmat.2012.02.038

This study examined the potential of Pseudomonas aeruginosa abundance in the intestines of fish as an indicator of exposure to benzo[a]pyrene (BaP). P. aeruginosa populations were enumerated in juvenile African catfish (Clarias gariepinus) injected intramuscularly three days previous with 0, 10, 30, 40, 50 or 70mg/kg of BaP. Hepatic EROD and GST activities and biliary fluorescent aromatic compounds (FACs) 1-OH BaP, 3-OH BaP, 7,8-D BaP and BaP were quantified to investigate agreements between the new indicator and established fish biomarkers. The shape of bacterial population (logarithm of colony-forming unit) dose-response curve generally matched those of biliary FACs concentrations. Conversely, the EROD and GST dose-response curves were generally the mirror images of the bacterial population curve. Changes in intestinal P. aeruginosa population appear to be an indirect effect of BaP exposure because exposure to 0-100μg/ml BaP had no effect on P. aeruginosa populations grown on agar plates containing BaP. Using intestinal P. aeruginosa population of fish as a universal indicator of BaP pollution in aquatic environments is discussed.Conversely, the EROD and GST dose-response curves were generally the mirror images of the bacterial population curve.

Matched MeSH terms: Cytochrome P-450 CYP1A1/metabolism
The effects of intramuscular and intraperitoneal injections of benzo[a]pyrene on selected biomarkers in Clarias gariepinus

Karami A, Christianus A, Ishak Z, Syed MA, Courtenay SC

Ecotoxicol Environ Saf, 2011 Sep;74(6):1558-66.
PMID: 21636131 DOI: 10.1016/j.ecoenv.2011.05.012

This study investigated the dose-dependent and time-course effects of intramuscular (i.m.) and intraperitoneal (i.p.) injection of benzo[a]pyrene (BaP) on the biomarkers EROD activity, GST activity, concentrations of BaP metabolites in bile, and visceral fat deposits (Lipid Somatic Index, LSI) in African catfish (Clarias gariepinus). Intraperitoneal injection resulted in 4.5 times higher accumulation of total selected biliary FACs than i.m. injection. Hepatic GST activities were inhibited by BaP via both injection methods. Dose-response relationships between BaP injection and both biliary FAC concentrations and hepatic GST activities were linear in the i.p. injected group but nonlinear in the i.m. injected fish. Hepatic EROD activity and LSI were not significantly affected by BaP exposure by either injection route. We conclude that i.p. is a more effective route of exposure than i.m. for future ecotoxicological studies of PAH exposure in C. gariepinus.

Matched MeSH terms: Cytochrome P-450 CYP1A1/metabolism
Inhibitory effect of phenethyl isothiocyanate against benzo[a] pyrene-induced rise in CYP1A1 mRNA and apoprotein levels as its chemopreventive properties

Abdull Razis AF, Konsue N, Ioannides C

Asian Pac J Cancer Prev, 2015;16(7):2679-83.
PMID: 25854346

BACKGROUND: Phenethyl isothiocyanate (PEITC), the most comprehensively studied aromatic isothiocyanate, has been shown to act as an anti-cancer agent mainly through modulation of biotransformation enzymes responsible for metabolizing carcinogens in the human body. Humans are often exposed to carcinogenic factors, some of which through the diet, such as polycyclic aromatic hydrocarbon benzo[a]pyrene via the consumption of over-cooked meats. Inhibition of the enzymes responsible for the bioactivation of this carcinogen, for example CYP1A1, the major enzyme required for polycyclic aromatic hydrocarbons (PAHs) bioactivation, is recognized as a chemoprevention strategy.
OBJECTIVE: To evaluate the inhibitory effects of PEITC against benzo[a]pyrene-induced rise in rat liver CYP1A1 mRNA and apoprotein levels.
MATERIALS AND METHODS: Precision cut rat liver slices were treated with benzo[a]pyrene at 1 and 5 μM in the presence of PEITC (1-25 μM) for 24 hours, followed by determination of CYP1A1 mRNA and apoprotein levels using quantitative polymerase chain reaction and immunoblotting.
RESULTS: Findings revealed that PEITC inhibited benzo[a]pyrene-induced rise in rat liver CYP1A1 mRNA in a dose-dependent manner as well as the apoprotein levels of CYP1A.
CONCLUSIONS: It was demonstrated that PEITC can directly inhibit the bioactivation of benzo[a]pyrene, indicating chemopreventive potential.

Matched MeSH terms: Cytochrome P-450 CYP1A1/metabolism*
Fulltext CYP2S1 and CYP2W1 mediate 2-(3,4-dimethoxyphenyl)-5-fluorobenzothiazole (GW-610, NSC 721648) sensitivity in breast and colorectal cancer cells

Tan BS, Tiong KH, Muruhadas A, Randhawa N, Choo HL, Bradshaw TD, et al.

Mol. Cancer Ther., 2011 Oct;10(10):1982-92.
PMID: 21831963 DOI: 10.1158/1535-7163.MCT-11-0391

Both 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F-203; NSC 703786) and 2-(3,4-dimethoxyphenyl)-5-fluorobenzothiazole (GW-610; NSC 721648) are antitumor agents with novel mechanism(s). Previous studies have indicated that cytochrome (CYP) P450 1A1 is crucial for 5F-203 activity. In the present study, we investigated the functional role of 2 newly identified CYP P450 enzymes, CYP2S1 and CYP2W1, in mediating antitumor activity of benzothiazole compounds. We generated isogenic breast cancer (MDA-MB-468, MCF-7) and colorectal cancer (CRC; KM12 and HCC2998) cell lines depleted for CYP1A1, CYP2S1, or CYP2W1. The sensitivity of these cells to 5F-203 and GW-610 was then compared with vector control cells. 5F-203 exhibited potent activity against breast cancer cells, whereas GW-610 was effective against both breast and colorectal cancer cells. CYP1A1 was induced in both breast cancer and CRC cells, while CYP2S1 and CYP2W1 were selectively induced in breast cancer cells only following treatment with 5F-203 or GW-610. Depletion of CYP1A1 abrogated the sensitivity of breast cancer and CRC cells to 5F-203 and GW-610. Although depletion of CYP2S1 sensitized both breast cancer and CRC cells toward 5F-203 and GW-610, CYP2W1 knockdown caused marked resistance to GW-610 in CRC cells. Our results indicate that CYP-P450 isoforms, with the exception of CYP1A1, play an important role in mediating benzothiazole activity. CYP2S1 appears to be involved in deactivation of benzothiazoles, whereas CYP2W1 is important for bioactivation of GW-610 in CRC cells. Because CYP2W1 is highly expressed in colorectal tumors, GW-610 represents a promising agent for CRC therapy.

Matched MeSH terms: Cytochrome P-450 CYP1A1/metabolism
Antitumour benzothiazoles. Part 32: DNA adducts and double strand breaks correlate with activity; synthesis of 5F203 hydrogels for local delivery

Stone EL, Citossi F, Singh R, Kaur B, Gaskell M, Farmer PB, et al.

Bioorg Med Chem, 2015 Nov 01;23(21):6891-9.
PMID: 26474663 DOI: 10.1016/j.bmc.2015.09.052

Potent, selective antitumour AhR ligands 5F 203 and GW 610 are bioactivated by CYPs 1A1 and 2W1. Herein we reason that DNA adducts' generation resulting in lethal DNA double strand breaks (DSBs) underlies benzothiazoles' activity. Treatment of sensitive carcinoma cell lines with GW 610 generated co-eluting DNA adducts (R(2)>0.7). Time-dependent appearance of γ-H2AX foci revealed subsequent DNA double strand breaks. Propensity for systemic toxicity of benzothiazoles steered development of prodrugs' hydrogels for localised delivery. Clinical applications of targeted therapies include prevention or treatment of recurrent disease after surgical resection of solid tumours. In vitro evaluation of 5F 203 prodrugs' activity demonstrated nanomolar potency against MCF-7 breast and IGROV-1 ovarian carcinoma cell lines.

Matched MeSH terms: Cytochrome P-450 CYP1A1/metabolism
The selective cytotoxicity of the alkenyl glucosinolate hydrolysis products and their presence in Brassica vegetables

Kadir NH, David R, Rossiter JT, Gooderham NJ

Toxicology, 2015 Aug 6;334:59-71.
PMID: 26066520 DOI: 10.1016/j.tox.2015.06.002

Cruciferous vegetable consumption correlates with reduced risk of cancer. This chemopreventative activity may involve glucosinolates and their hydrolysis products. Glucosinolate-derived isothiocyanates have been studied for their toxicity and chemopreventative properties, but other hydrolysis products (epithionitriles and nitriles) have not been thoroughly examined. We report that these hydrolysis products differ in their cytotoxicity to human cells, with toxicity most strongly associated with isothiocyanates rather than epithionitriles and nitriles. We explored mechanisms of this differential cytotoxicity by examining the role of oxidative metabolism, oxidative stress, mitochondrial permeability, reduced glutathione levels, cell cycle arrest and apoptosis. 2-Propenylisothiocyanate and 3-butenylisothiocyanate both inhibited cytochome P450 1A (CYP1A) enzyme activity in CYP expressing MCL-5 cells at high cytotoxic doses. Incubation of MCL-5 cells with non-cytotoxic doses of 2-propenylisothiocyanate for 24h resulted in a dose-dependent inhibition of ethoxyresorufin O-deethylase, yet failed to affect CYP1A1 mRNA expression indicating interference with enzyme activity rather than inhibition of transcription. Increased reactive oxygen species (ROS) production was observed only for 2-propenylisothiocyanate treatment. 2-Propenylisothiocyanate treatment lowered reduced glutathione levels whereas no changes were noted with 3,4-epithiobutylnitrile. Cell cycle analysis showed that 2-propenylisothiocyanate induced a G2/M block whereas other hydrolysis products showed only marginal effects. We found that 2-propenylisothiocyanate and 3-butenylisothiocyanate induced cell death predominantly via necrosis whereas, 3,4-epithiobutylnitrile promoted both necrosis and apoptosis. Thus the activity of glucosinolate hydrolysis products includes cytotoxicity that is compound-class specific and may contribute to their putative chemoprotection properties.

Matched MeSH terms: Cytochrome P-450 CYP1A1/metabolism